Issue with nocmodl when if statement is used in DERIVATIVE block about nrn HOT 7 CLOSED

So

DERIVATIVE states { 
  if (enable) {  
    m' = (1.0 - m) * 0.1
  }
}

translates to correct c syntax.

from nrn.

I will try to fix that , but it still won't be a valid model unless the states block is written

DERIVATIVE states   {
    if (enable == 1) {
      m' = (mInf-m)/mTau
      h' = (hInf-h)/hTau
    }else{
      m' = 0
      h' = 0
    }
}

from nrn.

There does not seem to be any easy way to fix this internally. I recommend you use the style

DERIVATIVE states   {
  LOCAL mt, ht
    if (enable == 1) {
      mt = 1/mTau
      ht = 1/hTau
    }else{
      mt = 0
      ht = 0
    }
    m' = (mInf-m)*mt
    h' = (hInf-h)*ht
}

from nrn.

Hi Michael,

This was asked by Giuseppe for structural plasticity simulation. What we would like to do is:

• there are lot of potential synapses in structural circuit
• there is a flag (range variable) that indicate whether synapse is active or not
• depending on flag, we want to completely skip execution of DERIVATIVE and BREAKPOINT block to reduce computation cost

Is there any way to achieve this? The suggestion you mentioned above wouldn't solve computational cost.

from nrn.

The following removes most of the computational cost of the cnexp method but at the cost of disallowing
cvode for the model. You may wish to introduce an if statement to surround the i=m*v in the BREAKPOINT to set i=0.

NEURON {
  SUFFIX temp
  NONSPECIFIC_CURRENT i
  RANGE enable
}

PARAMETER {
  enable = 1
}

ASSIGNED {
  v
  i
}

STATE {
  m
}

INITIAL {
  m = 0
}

BREAKPOINT {
  SOLVE proc
  i = m*v
}
 
PROCEDURE proc() {
  if (enable) {   
    SOLVE states METHOD cnexp
  }     
}

DERIVATIVE states {   
  m' = (1.0 - m) * 0.1
}

from nrn.

1. Is it possible to have a fix that does not disable CVODE?

2. I believe Giuseppe mentioned that changing all mod files with an if statement wouldnt be ideal because whoever would take over after his departure wouldn't understand the rationale.

from nrn.

A fix is pushed for missing trailing tokens (when they exist) when _ode_matsol%d functions are generateed

from nrn.